Your Cooking Oil May Be Harming Your Sleep

We already know that the home environment can have a big influence on sleep quality — the presence of mold, light pollution, and noise are known to make sleep more difficult. Now it appears that using cooking oil may have a negative effect on sleep, too.

Cooking oil fumes are produced and released whenever food is fried, stir-fried, or grilled using cooking oils at high temperatures. Although our exposure to such fumes is small when cooking at home, long-term exposure can cause health
problems. Studies have found that kitchen workers are more susceptible to oxidative DNA damage associated with exposure to such fumes.

A 2017 study published in the journal Environmental Pollution set out to determine whether cooking oil fumes affect sleep quality. Researchers recruited 2,197 participants with an average age of 37 years. The sleep quality of each participant was assessed using the Pittsburgh Sleep Quality Index (PSQI). Their exposure to cooking oil fumes was measured using a questionnaire on cooking habits and the cooking environment along with a urine test for the presence of urinary 1-hydroxypyrene — a biomarker of exposure to cooking oil fumes.

Researchers found that those with poor sleep quality (determined by a PSQI score greater than five) were more likely to:

Report poor kitchen ventilation

Preheat oil to smoking point

Spend more than 30 minutes cooking

After further analysis, researchers found that participants who reported poor kitchen ventilation were nearly twice as likely to report sleep disturbances, while those who preheated oil to smoking point and cooked for longer than 30 minutes were approximately one-and-a-half times more likely to report sleep disturbances.

When researchers analyzed urine samples from participants, those with high levels of urinary 1-hydroxypyrene were more than twice as likely to report poor overall sleep quality.

Why do cooking oil fumes appear to harm our sleep?

The short answer is, we don’t know! More studies are needed to investigate the potential link between exposure to cooking oil fumes and sleep quality before we can definitively conclude that cooking oil fumes harm sleep.

Are all cooking oils created equal?

In 2010, researchers compared the emissions of volatile organic compounds formed when heating coconut, safflower, canola, and extra virgin olive oils. They found that emissions drastically increased when oils began to smoke, implying that low smoke point oils may not be the best option for deep-frying. The authors found canola oil generated the lowest levels of volatile chemicals while coconut oil generated the most.

With that being said, research published in 2014 suggested that vegetable oils such as corn oil and sunflower oil emitted up to three times more aldehydes (another harmful byproduct of cooking) compared to butter — with coconut oil being found to emit the lowest amounts.

If you’re feeling confused, you aren’t alone! Although the International Agency for Research on Cancer (IARC) determined that emissions from high temperature frying are probably carcinogenic to humans, they found that neither frying method nor type of oil appeared to have a big influence on their results.

Martin Reed

Martin is the creator of Insomnia Coach, an eight-week course that combines online sleep education with individual sleep coaching. His course helps clients improve their sleep so they can enjoy a better life with more energy and start each day feeling happy, healthy, rested, and refreshed. Martin also runs a free sleep training course that has helped over 5,000 insomniacs. He holds a master’s degree in health and wellness education and studied clinical sleep health at the University of Delaware.